[BUG #7710] silence 'npm install' warnings in WebsiteWidgetBrowser

- add package.json:description
- had to add a 'readme.txt' file, too
[BUG #7710] add 'grunt sass' and 'npm install'

- 'grunt sass' in component/website
- 'npm install' in both websitewidgetbrowser and component/website,
  as this is necessary in a plain repo checkout